(function($) {

    $.alerts = {

        // These properties can be read/written by accessing $.alerts.propertyName from your scripts at any time

        verticalOffset: -75,                // vertical offset of the dialog from center screen, in pixels
        horizontalOffset: 0,                // horizontal offset of the dialog from center screen, in pixels/
        repositionOnResize: true,           // re-centers the dialog on window resize
        overlayOpacity: 0.5,                // transparency level of overlay
        overlayColor: '#000',               // base color of overlay
        draggable: true,                    // make the dialogs draggable (requires UI Draggables plugin)
        okButton: ' 确定 ',         // text for the OK button
        cancelButton: ' 关闭 ', // text for the Cancel button
        dialogClass: null,                  // if specified, this class will be applied to all dialogs

        // Public methods

        alert: function(message, title, callback) {
            if (title == null) title = 'Alert';
            $(function() {
                $.alerts._show(title, message, null, 'alert', function(result) {
                    if (callback) callback(result);
                });

            });
        },

        confirm: function(message, title, callback) {
            if (title == null) title = 'Confirm';
            $(function() {
                $.alerts._show(title, message, null, 'confirm', function(result) {
                    if (callback) callback(result);
                });
            });
        },

        prompt: function(message, value, title, callback) {
            if (title == null) title = 'Prompt';
            $(function() {
                $.alerts._show(title, message, value, 'prompt', function(result) {
                    if (callback) callback(result);
                });
            });
        },

        // Private methods

        _show: function(title, msg, value, type, callback) {

            $.alerts._hide();
            $.alerts._overlay('show');

            $("BODY").append(
			  '<div id="popup_container">' +
			    '<h1 id="popup_title"></h1>' +
			    '<div id="popup_content">' +
			      '<div id="popup_message"></div>' +
				'</div>' +
			  '</div>');

            if ($.alerts.dialogClass) $("#popup_container").addClass($.alerts.dialogClass);

            // IE6 Fix
            var pos = ($.browser.msie && parseInt($.browser.version) <= 6) ? 'absolute' : 'fixed';

            $("#popup_container").css({
                position: pos,
                zIndex: 99999,
                padding: 0,
                margin: 0
            });

            $("#popup_title").text(title);
            $("#popup_content").addClass(type);
            $("#popup_message").html(msg);

            $("#popup_container").css({
                minWidth: $("#popup_container").outerWidth(),
                maxWidth: $("#popup_container").outerWidth()
            });

            $.alerts._reposition();
            $.alerts._maintainPosition(true);

            switch (type) {
                case 'alert':
                    $("#popup_message").after('<div id="popup_panel"><input type="button" value="' + $.alerts.okButton + '" id="popup_ok" /></div>');
                    $("#popup_ok").click(function() {
                        $.alerts._hide();
                        callback(true);
                    });
                    $("#popup_ok").focus().keypress(function(e) {
                        if (e.keyCode == 13 || e.keyCode == 27) $("#popup_ok").trigger('click');
                    });
                    break;
                case 'confirm':
                    $("#popup_message").after('<div id="popup_panel"><input type="button" value="' + $.alerts.okButton + '" id="popup_ok" /> <input type="button" value="' + $.alerts.cancelButton + '" id="popup_cancel" /></div>');
                    $("#popup_ok").click(function() {
                        $.alerts._hide();
                        if (callback) callback(true);
                    });
                    $("#popup_cancel").click(function() {
                        $.alerts._hide();
                        if (callback) callback(false);
                    });
                    $("#popup_ok").focus();
                    $("#popup_ok, #popup_cancel").keypress(function(e) {
                        if (e.keyCode == 13) $("#popup_ok").trigger('click');
                        if (e.keyCode == 27) $("#popup_cancel").trigger('click');
                    });
                    break;
                case 'prompt':
                    $("#popup_message").append('<br /><input type="text" size="30" id="popup_prompt" />').after('<div id="popup_panel"><input type="button" value="' + $.alerts.okButton + '" id="popup_ok" /> <input type="button" value="' + $.alerts.cancelButton + '" id="popup_cancel" /></div>');
                    $("#popup_prompt").width($("#popup_message").width());
                    $("#popup_ok").click(function() {
                        var val = $("#popup_prompt").val();
                        $.alerts._hide();
                        if (callback) callback(val);
                    });
                    $("#popup_cancel").click(function() {
                        $.alerts._hide();
                        if (callback) callback(null);
                    });
                    $("#popup_prompt, #popup_ok, #popup_cancel").keypress(function(e) {
                        if (e.keyCode == 13) $("#popup_ok").trigger('click');
                        if (e.keyCode == 27) $("#popup_cancel").trigger('click');
                    });
                    if (value) $("#popup_prompt").val(value);
                    $("#popup_prompt").focus().select();
                    break;
            }

            // Make draggable
            if ($.alerts.draggable) {
                try {
                    $("#popup_container").draggable({ handle: $("#popup_title") });
                    $("#popup_title").css({ cursor: 'move' });
                } catch (e) { /* requires jQuery UI draggables */ }
            }
        },

        _hide: function() {
            $("#popup_container").remove();
            $.alerts._overlay('hide');
            $.alerts._maintainPosition(false);
        },

        _overlay: function(status) {
            switch (status) {
                case 'show':
                    $.alerts._overlay('hide');
                    $("BODY").append('<div id="popup_overlay"></div>');
                    $("#popup_overlay").css({
                        position: 'absolute',
                        zIndex: 99998,
                        top: '0px',
                        left: '0px',
                        width: '100%',
                        height: $(document).height(),
                        background: $.alerts.overlayColor,
                        opacity: $.alerts.overlayOpacity
                    });
                    break;
                case 'hide':
                    $("#popup_overlay").remove();
                    break;
            }
        },

        _reposition: function() {
            var top = (($(window).height() / 2) - ($("#popup_container").outerHeight() / 2)) + $.alerts.verticalOffset;
            var left = (($(window).width() / 2) - ($("#popup_container").outerWidth() / 2)) + $.alerts.horizontalOffset;
            if (top < 0) top = 0;
            if (left < 0) left = 0;

            // IE6 fix
            if ($.browser.msie && parseInt($.browser.version) <= 6) top = top + $(window).scrollTop();

            $("#popup_container").css({
                top: top + 'px',
                left: left + 'px'
            });
            $("#popup_overlay").height($(document).height());
        },

        _maintainPosition: function(status) {
            if ($.alerts.repositionOnResize) {
                switch (status) {
                    case true:
                        $(window).bind('resize', $.alerts._reposition);
                        break;
                    case false:
                        $(window).unbind('resize', $.alerts._reposition);
                        break;
                }
            }
        }

    }

    // Shortuct functions
    jAlert = function(message, title, callback) {
        $.alerts.alert(message, title, callback);
    }

    jConfirm = function(message, title, callback) {
        $.alerts.confirm(message, title, callback);
    };

    jPrompt = function(message, value, title, callback) {
        $.alerts.prompt(message, value, title, callback);
    };

})(jQuery);